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Make A Well-Grounded (Earthed) Fence
Tips from a New Zealand grazing farmer and consultant to
keep your fence hot and your livestock in.
By Vaughn Jones
Editor's note: Noted New
Zealand grazing farmer and consultant, Vaughn Jones, has been building and
troubleshooting electric fences since 1954. Here he provides a checklist of
advice and tips to solve one of the most common causes of fencing failure: Poor
grounding -- or "earthing" as they say "down under."
Guide to Good Grounding
Testing an Earth System
Poor Earthing Costs Production
Lightning Protection & Finding Shorts
your fence to function correctly, your earth (ground) system must be perfect.
But very few are, despite the instructions provided with most energizers. Also
I've not seen an instruction book with complete details of how to achieve
perfect earthing and completely trouble-free operation in all respects. So I'll
give all I know here:
Most farms seem to have earth systems which can't
cope with the flow of electrons coming back to it from fences with poor
insulation, leakage into vegetation, and the occasional wire which breaks and
touches the ground or touches a non-insulated wire. Energizers have become more
powerful, but many ground systems and their recommendations have not kept up
When the energiser (charger) earth system can't handle the increased
flow of electrons, they find other ways of getting back to the power supply
earth system. Unfortunately they sometimes do this through the cows and milking
machine, and through steel water pipes or the water in plastic pipes.
Guide to Good Grounding
When the energiser earth system can't absorb the increased flow of
electrons from leakage, electrons find other ways of getting back to the power
supply earth system. Energisers put out thousands of volts, and just one volt
through the cow's mouth or teats can upset her. Here are methods to follow to
- The energiser earth system must be installed well away -- at least 10 m (33
feet) from mains power earth peg, preferably on the opposite side of the
- Use 25-mm (1-inch) or larger diameter new or near new galvanised pipe
driven as deeply as possible into a moist soil, each at least 10 m (33 feet)
apart. Thin, black or rusty fence posts or similar are not suitable. Rust is a
bad conductor. A large surface area is needed to give a large contact area
between the soil and pipe.
- One metre (3 feet) of earth pipe per joule of output of the energiser is
usually sufficient for satisfactory earthing in conductive soils. Long earth
pipes which are driven deep into the soil give far better earthing than the same
total length at shallower depths because soils are more moist and have more
conductive minerals at lower levels. Two 3- metre-long pipes are better than
three 2-metre-long pipes when driven deeply this way. Large diameter pipes have
a greater soil contact surface, so are better than thin rods.
- Install the earth system well way from water pipes and bores which are
being used. But an unused steel pipe bore can be an excellent earth if it's not
rusted or broken.
- Connect the terminal marked Earth or Ground to the earth pipes by one
continuous length of double insulated electric fence leadout cable -- not
household or industrial cables which are made for only 400 volts, not for
10,000 volts. The cable should contain 2.5-mm (16-gauge) galvanised wire --
not thinner and not copper wire, which causes electrolysis at
the joins. Bare and clamp the cable securely to each pipe with galvanised
clamps. Ordinary galvanized wire can rust where it is damaged or touches the
ground. Using cable eliminates this.
- It is best to have no voltage on the earth system, but a maximum of 200
volts (and up to 300 volts on a large energizer) are acceptable when the fence
has been shorted out to as low a voltage as possible.
- Soils are not good conductors, so electrons spread out inclining towards
moist and mineral soils when travelling back to the energizer. Aim for a moist
area, work out a system of keeping the area around the earth pipes moist. If
necessary, take a galvanised wire along the bottom of a fence to a moist area,
and then install more earth stakes at that point. If the distance exceeds 100
metres, use two wires. Better still, use aluminium or aluminium-coated wire
which is up to three times more conductive than the same thickness galvanised
- Some soils are very bad conductors. If you have dry peat, pumice, volcanic
ash soils, etc., or soils that are dry at any time of the year, and there is no
wet area within a few hundred metres which could be used, a bentonite earthing
system can be bought and used. They are a good value. The bentonite mix is made
into a slurry and poured down 75-mm (3-inch) diameter or larger holes with pipes
set in the centre. Keep them moist. This system can improve earthing by up to
- In extremely dry areas and on snow, use an earth wire return system. This
is where there is an equal number of live and earth wires kept well apart on the
fence. The earth wires are joined with joint clamps (like the live wires) and
connected to the energized earth terminal. The earth wires should also be
earthed adequately (no voltage on them) every kilometre. These also act as
lightning conductors, keeping it away from energizers.
Testing an Earth System
Doing all the above reduces the chances of clicks on your radio and
- Testing an earth system without the fencing shorted out is a waste of time.
You must create a flow of electrons to load the earth system before testing it.
- Also testing the earth by holding the last earth pipe can be a waste of
time if the wire between it and the energiser is broken.
- To test the earth system, first short the fence out with steel rods at
least 100 metres from the earth system. Then use a digital voltmeter to measure
the voltage between the energiser earth terminal and an independent earth wire.
This should be pushed as far as possible (about one metre) into damp ground in a
position handy to the energizer and several metres away from any other earth
- To lower the voltage on the earth system add more earth pipes and/or
connect the earth wire to the bottom wire of a conventional fence.
- Never use your water supply, bore or well as a ground or allow a
charger ground wire to touch them or any part of buildings. It can cause shocks
in the water and stop animals from drinking, and buildings can become a
transmitting aerial for radio and phone interference.
- Double insulated underground cable should be used for the ground as well as
the live wire. Unused bore pipes or steel well liners are usually good grounds.
- Many New Zealand farmers measure Joules (energy) roughly by holding the
live wire and feeling the kick in good insulated gumboots standing on one foot
to halve the electrons flowing through your body. Caution: Don't do
this if you have a dicky ticker or Pacemaker.
- High-power energizers are essential for to controlling animals where long
lengths of wire are electrified. The high power is on for the very short period
of 0.0003 seconds which makes them safe.
- Voltage measured at the energizer is useless, especially if the fence wire
is thin, limited to one wire or has bad connections. But voltage can be an
indicator of the energy when measured at the end of a long fence.
- The latest, best New Zealand energizers have a system of telling the farmer
at the energizer the effectiveness of the fence at various points, and the earth
condition, both of which are extremely clever.
- The lower the voltage on the ground the better it is. But with high-power
energizers, it can be difficult to get the voltage below 200 volts, which figure
is acceptable (provided it was measured when the fence was shorted (grounded) a
few hundred metres from the energizer).
- Ensure that all electrical appliances wirings, everything metal and all
concrete steel reinforcing are all connected by welding or strong galvanised
clamps, not electroplated ones which rust sooner.
- If your stock are going through fences, check the earth first, followed by
the joints on the whole fence, and at the same time look for shorts.
- Test your earth by thoroughly shorting out the fence at least 100 metres
(330 feet) away from the energiser with steel standards. Doing this creates the
maximum current flow so puts a load on the earth system. If your earth pipes
can't handle the flow you'll get a voltage reading at the energizer terminals.
If there is no voltage, then your earthing system is satisfactory.
- You should have a digital voltmeter, then install an earth monitoring point
by pushing a piece of 4-mm (8-gauge) wire into the ground handy to the energiser
and measure between it and the energiser earth terminal. Don't check the last
earth pipe because there could be a break in the wire to it, in which case
you'll think the earth is OK, but it may not be.
- With the fence shorted out, there should be no more than 200 volts,
although no voltage reading is best. The more voltage you read flowing to your
earth, the less power you will have on your fence because it indicates that the
earth is inadequate and needs more pipes.
- To improve your earth system, increase the number of earth pipes and put
them in as deep as possible. Tests on several soil types have shown that depth
is essential -- 2 m (6 feet) deep is the minimum, and 3 m (9 feet) deep is twice
An inadequate earth system reduces the output of your energiser and
increases the chances of shocks in milking parlors, yards and water troughs. It
takes an expert with sensitive measuring equipment left connected for 24 hours
and a recorder to check for shocks in parlors. There may be none during the day,
but they can occur when heaters, cookers, etc., are switched on in the late
Check your parlor twice a year and yards in many positions
at the height of dry weather and the height of the wet period. See your
energiser installation instructions for more details on installing it and an
Poor Earthing Costs Production
A common problem is having energiser earth pipes behind the milking
parlor. Leaked electrons (there are always some) flow from the farm under the
yard and parlor when the soil is moist. But when it is dry, they look for
easier routes, which can be across a moist yard and through parlor pipe work.
In wet weather, electrons can travel along the soil surface and
through the parlor, especially after cows enter and pass their high mineral,
highly conductive urine. This can cause electrons to even flow across the
concrete surface and across pipe work, so affecting the cows.
or weeds conducting power off a live wire close to the parlor can result in
electrons flowing through the parlor and/or yard because it is the shortest
route, especially after cows enter and urinate. The above can occur even when
the earth system is perfect, simply because the electrons are flowing to it via
the best, shortest and fastest route.
To avoid this, earth systems should be in a damp area well to the side
of the milking parlor, or even have earth pipes well to both sides, but never in
line with the parlor. The earth leadout wire from the energiser should be
insulated, and not allowed to touch any other wire, building or pipe.
Electrons can also move through water pipes, giving shocks to cows
when drinking in a paddock, so no wires should be allowed to touch water
troughs. Even if not electrified, they can conduct induced current. Cows
standing around a full trough waiting to drink can be a sign of power deterring
them from drinking.
Where conventional fences have a live wire running with them or as an
offset wire, the conventional fence wires can absorb induced current (more so in
damp conditions) and become electrified. So unelectrified wires must be earthed
or they can build up a voltage which can:
Earthing these conventional fence lines is
easy because being induced power, it is of low joules (energy or power). All
they need is a piece of soft galvanized wire wrapped around all dead wires at
the strainer posts and pushed into the soil. These will need replacing when they
rust at ground level.
- Jump gaps (bad joins) and cause sparks and radio and phone interference.
- Conduct current to water troughs they may touch. Animals then won't drink
so growth and milk production suffer, and females can get cysts on their ovaries
through stress. This happened to a herd near here causes calculated losses of
$30,000 over the years it had been happening.
- Give people shocks when opening and closing gates.
- Give animals shocks as they go through gateways and brush against the wires
tied around strainer posts.
Shocks in sheds and water troughs have cost some farmers small
fortunes in lost production over several years, until the problem was
identified. New Zealand manufacturers discourage grounding the fence circuit
though the earth or ground terminal of the charger to the utility (power supply)
grounding system because it is illegal in many countries and can cause shocks in
all directions including in your shower. The power supply ground is usually just
a metre deep rod. A modern high power New Zealand energizer needs ten to twenty
Keep these in mind when
you build fence:
The thought of 5,000 volt fences on farms near cities could be
frightening to townies, but thousands of human contacts occur annually with
nothing more than discomfort. However, care should be taken to avoid contact
through the head because it is very uncomfortable. Young children and elderly
people should be kept away from even low powered fences.
- Don't string wires across lanes or thoroughfares without marking them
clearly. Motor cyclists have been injured through not seeing them.
- Never electrify barbed wire.
- Train and demonstrate the shock to children and visitors with a long piece
Electrified fences in any position where the public could come in
contact with them must be clearly marked with approved warning signs at
frequent enough intervals so as to be easily seen.
It is an offence to operate any appliance which causes any electronic
interference, so points to note include:
You might find this difficult.
Having changes in the fence to under-gate cable reduces the length of "aerial"
electric fence wire. It is long lengths of electric fence wire parallel with
long lengths of telephone or similar wires which cause the problem which can
grow as the fences are extended over time. The closer they are the more the
induction. The break causing the spark and interference can then be on the
- Some energizers cause more radio and/or phone interference than others,
even if not on a fence. Switch it off, disconnect the fence and earth (ground)
cables (wires) at the energizer (if they were loose the sparking there could
cause interference) and switch on the energizer and check for interference.
- If the interference is still there, return the energizer to the supplier
and try another unit or brand. Some brands are bad.
- If the interference disappears when the fence and earth are disconnected:
- Tighten all joins and clamps on the energizer and fences. Those on some
energizers work loose because of the thump (vibration).
- Ensure that all wire connections are figure of eight or reef knots, or are
clamped and tight.
- Tube insulators will crack and leak in time. Even double tubes and those
with steel inserts leak and spark in some cases.
- Sparking causes radio and telephone interference so insulators must be good
quality with adequate tracking distance to avoid arcing over the surface as
occurs with staple insulators or through the insulator as occurs with single
tubing. Use quality insulators with at least 25 mm (1 inch) of tracking distance
(length on insulator from the live wire to any other point).
- Some cable can have breaks in it causing sparking. Single insulated cable
gets cracks sooner than double. (Try bending a sheet of cardboard and a wad of
paper the same thickness and you'll see why. The card will crack.) Some of the
orange cable from New Zealand cracked and leaked soon after installing. Replace
- Even the best cable when buried can become damaged by a stone and then
leak. It is essential that all be threaded through 12 mm (half-inch) or similar
black plastic piping to give it physical protection. If the distance is long,
push a piece of high tensile wire (with its end bent back) through and then pull
the cable through. To check under gateways, disconnect before each one and check
if the interference stops.
- Ensure that the earth is perfect. Check it at the energizer, not at the
last earth pipe as shown on some instruction books. There could be a break in
the cable so there would be no voltage at the last, or even first pipe.
- The earth cable should be one continuous length of double insulated cable
or be joined with a good galvanised joint clamp, and must not touch any building
or pipe. Support the cable in good insulators.
- Use a digital volt meter to test the earth and to locate shorts and
maintain tidy, trouble-free fences.
- If you still have interference, tighten all joins and clamps on the farm.
This is best done in summer when joint clamps have expanded.
- Walk along all fences and wires with a radio tuned off the station and
clicking. It will get louder close to the interference cause.
- Shorting to vegetation or to any grounded object can cause clicking, so
disconnect the bottom wire and/or clear the fence line with a weed wiper. Once
grass touches a live wire, stock won't graze it, or anywhere near it, so the
problem increases. Always have the bottom wire able to be disconnected with a
flexible connector and do so before vegetation touches it.
- The mains power supply (utility) earth and all connections including power
point terminals and plugs must be adequate with no loose or old verdigris
- If wires run parallel with overhead phone wires on underground phone cables
interference can be worse, so avoid the constructing of electrified fences
parallel to telephone lines or cables and aerials, or parallel to other long
fences which could act as aerials.
Radio interference is worse in poor reception areas, and if the radio
is not tuned exactly on the station. Telephone systems are not always perfect.
The long distances of
electric fencing now used increase the chance of a lightning strike, so an
effective protective system should be used. Lightning often hits the power
supply line and goes through the energizer to its earth system blowing its fuse
or components. The power (utility) supply earth system should be good enough to
attract the lightning rather than have it go through the energizer to its earth.
The solid state digital volt meter is important for fault finding and
for testing the earth system. It enables accurate reading of the voltage and
easy fault finding, because of its extreme accuracy.
Start by going to
the first switch (these must be installed along fence lines to save going back
to the energizer to switch it off for repairs and for fault finding) and see if
the voltage before the switch increases after opening the switch to stop current
flow down the farm.
If the voltage increases then go to the next
switch. If not check the fence between the switch and the energizer. Neon fence
testers are also available, but of no use for finding small leaks or earth
system faults. Many are bought and not used for long before buying a digital
Electric or power fencing helps make animal farming
profitable and sustainable, so the effort required to achieve the above
suggestions is well worthwhile. If installation is good and monitoring is done,
the labour required is less than with any other system and the profit is
If you have problems, read all the above again. There is a lot to
take in, but once you understand it, it becomes second nature.
Take pride in your fencing and enjoy your animals.
For more information, see:
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